On-demand unprotected mode access

ABSTRACT

Migrating support for a web browsing session between a virtual machine and a host operating system. A web session is supported by a first virtual machine which executes on a computer system. Upon receiving a request for the web session to enter an unprotected mode, support for the web session is migrated from the first virtual machine to a host operating system of the computer system. In unprotected mode, web sessions are supported by the host operating system rather than by a virtual machine. After migrating support for the web session to the host operating system, a visual cue indicating that the unprotected mode is active is displayed. After receiving a request to exit the unprotected mode, support for the web session is migrated from the host operating system to a second virtual machine executing on the computer system and the visual cue is removed.

CLAIM OF PRIORITY AND RELATED APPLICATION DATA

This application is related to U.S. non-provisional patent application Ser. No. 13/526,409, filed Jun. 18, 2012, entitled “Synchronizing Resources of a Virtualized Browser,” the contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.

This application is related to U.S. non-provisional patent application Ser. No. 13/526,403, filed Jun. 18, 2012, entitled “Synchronizing History Data Across a Virtualized Web Browser,” the contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.

This application is related to U.S. non-provisional patent application Ser. No. 13/526,390, filed Jun. 18, 2012, entitled “Synchronizing Cookie Data Using a Virtualized Browser,” the contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.

This application is related to U.S. non-provisional patent application Ser. No. 13/526,373, filed Jun. 18, 2012, entitled “Composing the Display of a Virtualized Web Browser,” the contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.

This application is related to U.S. non-provisional patent application Ser. No. 13/526,354, filed Jun. 18, 2012, entitled “Transferring Files Using a Virtualized Application,” the contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.

This application is related to U.S. non-provisional patent application Ser. No. 13/526,423, filed Jun. 18, 2012, entitled “Securing Resources of a Virtual Machine,” the contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.

This application is related to U.S. non-provisional patent application Ser. No. 13/419,345, filed Mar. 13, 2012, entitled “Seamless Management of Untrusted Data Using Virtual Machines” the contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.

FIELD OF THE INVENTION

Embodiments of the invention relate to migrating support for a web session between a virtual machine and a host operating system.

BACKGROUND

Ensuring the security of computer networks and network connected devices is one of the grand challenges facing us today. The current state of affairs is very problematic, as our cyber-security infrastructure is routinely subverted by cyber criminals, resulting in great economic loss, invasion of privacy, and loss of productivity.

Certain web browsers have attempted to provide a level of security by isolating downloaded code. However, present approaches for doing so are fairly primitive in their ability to deal with the full gamut of security issues that arise during the course of a typical user's web experience. For example, the sandboxing capability of certain versions of Google's web browser does not address safety issues arising from downloaded browser plugins and various types of native executables, and therefore, possesses a vulnerability to a zero day exploit attack that via Adobe Flash or Microsoft Word.

Web browser vendors rely upon monetizing the web browsing habits of their users within their own business processes and with their industry partners. This monetization relies, at least in part, on data about users' browsing habits which is stored in the web cookies that are set and later provided to web servers during the course of web sessions. Companies such as Google and Microsoft have a great interest in learning as much as possible about a person's browsing habits and typically arrange the default privacy settings of web browsers to be advantageous to them, but less than optimal from a security and privacy standpoint. The default privacy settings causes web browsers to transfer large amounts of sensitive information from users' machines to Internet related businesses, such as Google, Microsoft, Apple, etc., thereby allowing such businesses to better monetize their customer base by offering appropriate products and services and serving targeted ads. These same settings, however, can be leveraged by malicious parties to exploit security vulnerabilities. While all web browsers provide some level of control to the sophisticated user to tune his or her web browser privacy settings, the vast majority of users never change the default settings.

According to some current approaches for enhancing the security of a computer, the computer runs multiple independent operating systems using multiple virtual machines (VMs) within the computer. Multiple virtual machines may be created using a hypervisor, such as from VMware of Palo Alto, Calif. or Virtual PC, available from Microsoft Corporation of Redmond, Wash. When client virtualization is used to achieve improved security, different VMs are used to run different types or classes of applications. For example, an operating system in one VM may be dedicated for accessing the corporate network that the user may be part of and running corporate applications (local and web). Another operating system in a second VM might be used by the user to run his or her personal programs and store personal documents. Finally, a different operating system in a third VM may be used for general web browsing on the wider Internet and running native executables that may have been downloaded from the Internet. An example of such a solution is XenClient, which is made by Citrix Systems of Ft Lauderdale, Fla.

This use of classical client virtualization suffers from several drawbacks. One drawback is that there is too much management overhead for the end-user. The end-user has the onus of making the decision as to what VM to use for each activity. Any mistake, intentional or accidental, may subvert the integrity of the system. While many safeguards can be added as a layer on top of the core virtualization technology to help prevent the user from making mistakes, this has not yet been demonstrated to work in a practical and robust fashion.

Another drawback is that any VM that is used for general web browsing is just as vulnerable to a security problem as any monolithic system running a single VM while accessing web sites on the general Internet. Therefore, it is quite likely that any VM dedicated to web browsing described in the arrangement above will be subverted by malware eventually. Any subsequent activities in that VM, then, will be compromised.

For these and other reasons, client virtualization has not been used widely to improve the security of computer systems.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

FIG. 1 is a block diagram of system according to one embodiment of the invention;

FIG. 2 is a flowchart illustrating the steps of retrieving a web page using a virtualized web browser according to an embodiment of the invention;

FIG. 3 is a block diagram that illustrates a computer system upon which an embodiment of the invention may be implemented;

FIG. 4 is an illustration of injecting state data into a virtual machine according to an embodiment of the invention;

FIG. 5 is a flowchart illustrating the steps of migrating support for a web session from between a virtual machine and a host operating system according to an embodiment of the invention; and

FIG. 6 is a block diagram that illustrates a computer system upon which an embodiment of the invention may be implemented.

DETAILED DESCRIPTION OF THE INVENTION

Approaches for migrating support for a web session between a virtual machine and a host operating system are presented herein. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described herein. It will be apparent, however, that the embodiments of the invention described herein may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form or discussed at a high level in order to avoid unnecessarily obscuring teachings of embodiments of the invention.

Functional Overview

U.S. non-provisional patent application Ser. No. 13/526,409, filed Jun. 18, 2012, entitled “Synchronizing Resources of a Virtualized Browser,” discusses approaches involving a virtualized web browser. Using a virtualized web browser enables one to view web content safely, as untrusted content is retrieved and rendered within a virtual machine. However, from time to time it may be desirable to retrieve and render content using a virtualized web browser from within a host operating system. For example, if a script executing on a web page is not rendering properly within a virtual machine, it may be helpful to retrieve and render that web page in the host operating system for debugging purposes.

Embodiments of the invention advantageously allow support for a web browsing session to be migrating between a virtual machine and a host operating system. Using embodiments of the invention, a web browsing session that is being rendered in a first virtual machine may be re-rendered in the host upon request to enter an “unprotected mode.” An unprotected mode is a mode in which web sessions are supported by the host operating system rather than by a virtual machine. An embodiment may re-rendering a web browsing session in an unprotected mode by closing a web browser tab and opening a new web browser tab that displays the same content as the closed tab, except that the content was retrieved and rendered in the host operating system instead of a virtual machine.

A visual and/or other sensory cue may be provided to alert the user that browsing activity is being rendered in the host. For example, the web browser may display a graphic or image, or the color of certain portions of the web browser may change, to inform the user that the content displayed in the web browser, or just a tab thereof, is in the unprotected mode.

Once the user is finished with the particular web session that is being rendered in the host operating system, the user may issue a request to exit unprotected mode. For example, the user may close the web browser tab, navigate to a different web page, click the visual cue to turn off unprotected mode, and/or select an option from a menu (such as a menu displayed when a mouse button is pressed). Upon receiving an instruction to do so, the web browser may cause the web session to exit the unprotected mode and remove the visual cue associated therewith.

Virtualized Web Browser

Embodiments of the invention may be employed with a virtualized web browser. A virtualized web browser refers to a plurality of components that cooperate to provide a secure web browsing experience. A characteristic of a virtualized web browser is that a portion of the components implementing the virtualized web browser resides in the host while another portion of the components implementing the virtualized web browser resides in one or more virtual machines. While the portion of the virtualized web browser that resides in the host is responsible for displaying content, that portion need not retrieve the displayed content from across the network. Instead, the content displayed by a virtualized web browser is typically retrieved by components in one or more virtual machines, although the component(s) of the virtualized web browser residing in the host may retrieve and render content if desired.

A virtualized web browser presents the same user experience as a traditional (or “native”) web browser. A person using a virtualized web browser may, in fact, not even realize that they aren't using a traditional web browser. Therefore, a user of a virtualized web browser need not alter their usage patterns and may use a virtualized web browser in the same way as a traditional web browser.

As used herein, the term “web browser” will be used to refer to both traditional web browsers and virtualized web browsers. When specific reference is made to traditional web browsers (i.e., those web browsers which are not virtualized web browsers), the term “traditional web browsers” or “native web browsers” will be used herein.

The types of operations that are typically performed on a web browser include, without limitation, browsing to various web sites, entering information and logging into web pages, navigating back and forth between visited web pages, uploading and downloading content through a web page, and saving and using bookmarks. To support such activity, web browsers maintain temporary and persistent state information to ensure such operations are properly performed.

The desire to ensure that a virtualized web browser offers the same user experience as a traditional web browser requires that virtualized web browsers manage the temporary and persistent state information necessary to perform expected web browser operations across the underlying micro-virtualization environment in which these operations are performed. Many approaches will be presented herein for selectively synchronizing the cookies of a virtualized web browser, based on policy, so that the virtualized web browser provides a familiar user experience while operating in a secure manner. Prior to doing so however, a more detailed description of how a virtualized web browser of an embodiment operates will be presented.

Anatomy of a Virtualized Web Browser

To better appreciate how a virtualized web browser operates, consider FIG. 1, which is a block diagram of system 100 according to one embodiment of the invention. System 100 includes a virtualized web browser that has components that are implemented on the host as well as on different virtual machines. FIG. 1 depicts host 110 and virtual machines 120A, 120B, . . . 120N. Host 110 corresponds to the host operating system installed upon a device. Host 110 may be embodied by a wide variety of operating systems, either presently available or subsequently developed.

In an embodiment (not depicted in FIG. 1), the functional components residing in host 110 may instead reside in a persistently maintained virtual machine. Such an approach is discussed in U.S. patent application Ser. No. 13/526,755, entitled “Ensuring the Privacy and Integrity of a Hypervisor,” filed Jun. 19, 2012, the contents of which are incorporated by reference for all purposes herein.

Virtual machines 120A, 120B, . . . 120N each represent any type of virtual machine. In an embodiment, virtual machines 120A, 120B, . . . 120N may each correspond to a UCVM discussed in the '354 patent. While FIG. 1 only specifically identifies three virtual machines, namely virtual machines 120A, 120B, and 120N, the graphical notations of FIG. 1 are meant to convey that embodiments of the invention may employ any number of virtual machines. Moreover, during the normal course of operation, virtual machines may be periodically instantiated or destroyed, and so the particular number of virtual machines within system 100 will always be changing during normal operation.

Virtual machines 120A, 120B, . . . 120N may reside on the same physical machine as host 110, but they need not. In fact, one or more of virtual machines 120A, 120B, . . . 120N may reside on a different physical machine than on which host 110 resides and may communicate with host 110 over a network. For example, host 110 may be implemented on a cell phone, laptop computer, tablet computer, PC, or other device or computer, and virtual machines 120A, 120B, . . . 120N may be implemented on one or more separate physical machines located over a network. To facilitate the retrieval of web content, virtual machines 120A, 120B, . . . 120N may have a network connection. Note that the particular network settings and network configuration of virtual machines 120A, 120B, . . . 120N may be different and specifically tailored to suit the activity assigned thereto.

In a virtualized web browser of an embodiment, different virtual machines may be used to perform user initiated actions such as retrieving requested content from the Internet. Each of virtual machines 120A, 120B, . . . 120N is completely isolated from each other and from host 110. As shall be explained below in greater detail, the determination of which virtual machine a particular action should be performed in may be based on policy, as reasons will be discussed for wanting to perform certain actions together in the same virtual machine as well as reasons for wanting to perform various actions in separate virtual machines.

As shown in FIG. 1, host 110 comprises web browser 112 while virtual machines 120A, 120B, . . . 120N each comprise web browsers 122A, 122B, . . . 122N respectively. For clarity, web browsers 122A, 122B, . . . 122N shall be termed VM web browsers to signify that the web browsers execute within a virtual machine in system 100. By the same token, web browser 112 shall be termed host web browser 112 to signify that it executes within host 112.

A virtualized web browser of an embodiment is comprised of host web browser 112, one or more VM web browsers, such as VM web browsers 122A, 122B, and 122N, host module 114, and one or more guest modules, such as guest modules 124A, 124B, and 124N. Host module 114 and guest modules 124A, 124B, and 124N are components which assist in synchronizing resources of the virtualized web browser.

VM web browsers 122A, 122B, and 122N and other applications that are run on behalf of the virtualized web browser in each virtual machine store and update the state of a user's web browser session. However, since each VM web browser is running in an isolated virtual machine, the state changes made to the web browser session made by a particular virtual machine are local to that virtual machine. This provides complete isolation between various user actions, which assists in promoting security; however, isolating virtual machines from one another frustrates certain interfaces and behavior of a web browser that the user expects.

Therefore, host module 114 and guest modules 124A, 124B, and 124N cooperate to share information about certain changes made to the web browser session and synchronize resources when appropriate. The guest module within each virtual machine tracks the resources that are requested and updated by the VM web browser within that virtual machine. For example, guest module 124A within virtual machine 120A tracks the resources that are requested and updated by web browser 122A. Host module 114 coordinates resource synchronization between host 110 and virtual machines 120A, 120B, . . . 120N. Host module 114 and the guest modules within each virtual machine communicate over secure communication channels that are not accessible to possible insecure code running in virtual machines 120A, 120B, . . . 120N or in host 110.

Host module 114 and guest modules 124A, 124B, and 124N provide an interface to host web browser 112 so that information about the activity in virtual machines 120A, 120B, . . . 120N is shared as needed and reflected in the user experience provided by the virtualized web browser. As a result of the activity of host module 114 and guest modules 124A, 124B, . . . 124N, the user is not responsible for coordinating the activity of the underlying micro-virtualization of the virtualized web browser.

To illustrate the role played by host module 114 and guest modules 124A, 124B, . . . 124N, consider that the VM web browser in each virtual machine maintains its own list of history entries reflecting where that particular VM web browser navigated. However, the user expects that any navigations previously performed by him to show up in the history entries of the virtualized web browser regardless of which particular VM web browser was involved in the navigation. Therefore, operations involving a user's past navigation history should reflect the browsing history of the user regardless of which particular virtual machine was responsible for retrieving the web pages. Host module 114 and guest modules 124A, 124B, . . . 124N help ensure that relevant information about the user's browsing activity is shared appropriately between host 110 and virtual machines 120A, 120B, . . . 120N so that browsing history behaves as expected.

Another illustration of how host module 114 and guest modules 124A, 124B, . . . 124N synchronize resources of a virtualized web browser may be shown by their coordinated support for the use of APIs from popular web sites such as Facebook and Google on third-party web sites. When one visits a third party web site that is integrated with Facebook, the web browser ideally uses secure mechanisms to show content related to your Facebook account on the third party web site. For example, a news web site can show stories that your friends from Facebook “liked” on that news web site. These types of web page features typically use cookies or web protocols such as OAuth. Cookies are resources that are exchanged between the web browser and web sites being visited by the user. If VM web browser 122A executing in virtual machine 120A and the web site being browsed by VM web browser 122A exchange cookies, then the cookies will likely be needed in host 110 (and potentially in other virtual machines as explained below) to ensure that the display of the web page properly integrates with Facebook. Therefore, as shall be explained in more detail below, host module 114 and guest modules 124A, 124B, . . . 124N make sure that each virtual machine has the cookies necessary so that the VM web browser executing therein can properly display and render any web page retrieved by that VM web browser.

Operation of a Virtualized Web Browser

Embodiments of the invention seamlessly synchronize resources of a virtualized web browser to present a completely native browser experience to the end user. A wide variety of resources may be coordinated between host 110 and virtual machines 120A, 120B, . . . 120N including without limitation: URLs, screen data for all or at least a portion of a web page retrieved by VM web browser, user input (such as keyboard and mouse actions) directed against a web page displayed by a web browser, cookies, navigation history, bookmarks, configuration settings for the web browser, cache files of various types, DOM storage, and files saved and uploaded. Any type of data that indicates a change in state in the user's web browsing experience (“state data”) may be synchronized as appropriate between host 110 and virtual machines 120A, 120B, . . . 120N according to embodiments.

Prior to discussing in detail how these types of resources are synchronized, it will be helpful to understand how a virtualized web browser retrieves and displays a requested web page. FIG. 2 is a flowchart illustrating the steps of retrieving a web page using a virtualized web browser according to an embodiment of the invention.

In step 210, a user instructs a virtualized web browser to display a web page. As previously explained, the user may not know that the web browser he or she is using is a virtualized web browser, as the virtualized web browser will exhibit the appearance and behavior of a traditional web browser. However, in all actuality, when a user interacts with a virtualized web browser, the user is actually directly interacting with host web browser 112 executing in host 110.

The user actions taken with respect to host web browser 112 are identified by host module 114 in cooperation with host web browser 112. Embodiments may inform host module 114 of the user actions taken with respect to host web browser 112 using a variety of different techniques. Different types of web browsers and/or host operating system may provide different options for informing host module 114 of user actions directed against host web browser 112, and embodiments of the invention may employ any appropriate manner to do so. Non-limiting, illustrative mechanisms for enabling communication between host web browser 112 and host module 114 include APIs, callbacks, and web browser plug-ins. To recite one specific example, in an embodiment where host web browser 112 is a version of Microsoft Internet Explorer, then Browser Helper Objects (BHO) may be used to inform module 114 of user actions directed against host web browser 112. As another example, host web browser 112 may be augmented with a plug-in that causes host module 114 to be informed of any user input submitted to host web browser 112.

Once host module 114 identifies a user action directed against host web browser 112, host module 114 either performs the request action itself or forwards notice of the requested action to an appropriate virtual machine within system 100 for processing. Host module 114 may consult policy data to determine whether the user action should be processed within host 110 or within a particular virtual machine.

To provide a concrete example, assume the user action is a request to display a web page. Further assume that host module 114, in consultation with policy data, determines that virtual machine 120A is the appropriate virtual machine responsible for retrieving that web page.

In an embodiment, the particular virtual machine selected by host module 114 to process any user input or perform any requested user action will possess characteristics appropriate for the type of activity involved in doing so. In this example, virtual machine 120A should be configured to possess appropriate characteristics for retrieving the type of web page being requested. If the requested web page is a web page on an internal corporate intranet site, then virtual machine 120A should have appropriately tailored configuration settings to do so in a manner that addresses any security concerns. Similarly, if the requested web page is a web page associated with the user's personal bank or other such financial institution, then virtual machine 120A may have a different set of configuration settings to address the particular type of activity and level of risk involved

Virtual machine 120A need not be instantiated at the time host module 114 determines that virtual machine 120A should retrieve the web page, as virtual machine 120A may be instantiated on-the-fly. Host module 110 may instruct a hypervisor to create a particular virtual machine using a template that causes the particular virtual machine to have characteristics chosen for particular task at hand, namely retrieving a particular web page in this example. Any instantiated virtual machine will comprise a guest module and may comprise a VM web browser. Additional description of how virtual machines may be implemented on-the-fly with specifically tailored characteristics is described in the previously mentioned '354 patent.

To inform virtual machine 120A to retrieve the requested web page, host module 114 communicates an instruction to guest module 124A within virtual machine 120A to retrieve the requested web page. If VM web browser 122A is not instantiated at the time guest module 124A receives the instruction to retrieve the requested web page, then guest module 124A instantiates VM web browser 122A at that time.

In step 220, guest module 124A instructs VM web browser 122A to retrieve the requested web page. In response, VM web browser 122A retrieves the requested web page and renders the web page. Note that as VM web browser 122A is executing within virtual machine 120A, the rendering of the requested web page by VM web browser 122A will not cause the rendered web page to be visually displayed to the user by VM web browser 122A, but instead, the retrieved web page is merely interpreted without being shown upon a connected display device.

Instead, host web browser 112 is responsible for displaying the retrieved web page on a connected physical display device. To make this so, the visual appearance of the web page rendered by VM web browser 122A is shown as the web page displayed by host web browser 112. In other words, the content that was to be shown by VM web browser 122A is instead shown by host web browser 112.

There are many ways in which the screen of a VM web browser may be displayed to the user by host web browser 112. One way involves guest module 124A generating or obtaining a graphical representation (termed “screen data”) of the rendered web page. Screen data is a graphical depiction of at least a portion of the appearance of the web page. Screen data may represent the visual presentation of the entire web page or, as is performed by some embodiments, only a portion of the web page. For example, an uninterpreted web page may be represented as an HTML file, whereas screen data for that web page may be an image file, such as a file in a JPEG, TIF, PNG, or GIF format. Screen data may be embodied using any type of format for defining how to display content, such as a graphical representation.

In an embodiment, after guest module 124A obtains screen data for the requested web page, guest module 124A sends the screen data for the requested web page to host module 114.

In another embodiment, once screen data is generated for the requested web page, host module 114 retrieves the screen data for the requested web page from virtual machine 120A. For example, host module 114 may retrieve the contents from a predetermined location in memory at which the screen data is to be stored.

In an embodiment, other data besides screen data may be obtained by host module 114 in step 220. If guest module 124A retrieves a file or graphic in virtual machine 120A, then the graphic or file may be made available to host module 114. After host module 114 possesses screen data for the requested web page, processing proceeds to step 230.

In step 230, the virtualized web browser processes the data received in step 220 and displays the requested web page. In an embodiment, step 230 is performed by host module 114 instructing host web browser 112 to display the requested web page using the screen data received from guest module 124A. After doing so, the user may physically view the requested page upon a display device, as the visual representation of the web page may be displayed on a physical display device by host web browser 114.

Note that host web browser 112 may display the requested web page using the screen data with or without any visual indicators that identify that the requested web page, or any portion thereof, was not retrieved within host 110 or by host web browser 112. If the use of visual indicators is desired, a specifically-colored border or a window decoration of a special color may be used to denote the host windows or tabs that are being rendered in an untrusted virtual machine.

Using Multiple Virtual Machines to Retrieve a Single Requested Web Page

The description of FIG. 2 was presented in terms of a retrieving a requested web page using a single web browser executing on a single virtual machine. However, this need not be the case in all embodiments, as other embodiments may employ multiple virtual machines to retrieve different portions of a single requested web page. In such an embodiment, host web browser 112 would display the requested web page by displaying the assembled portions of screen data received from the two or more virtual machines involved in retrieving the different portions of the web page.

To further illustrate such an embodiment, consider FIG. 3, which is a block diagram illustrating which virtual machines in system 100 are responsible for retrieving and rendering portions of a single requested web page according to an embodiment of the invention. FIG. 3 depicts web page 310 that comprises two bounded areas of content 312 and 314. Bounded areas of content 312 and 314 may be identified using a HTML construct called an “iFrame.” The iFrame HTML tag is supported by all major web browsers and is a way to demarcate different portions of a web page. Within an iFrame, content may originate from a different source than the web page in which it resides. In other words, web page 310, content within iFrame 312, and content within iFrame 314 may each originate from a different source on the Internet.

When host module 114 receives a request to display a web page, host module 114 may instruct multiple virtual machines to return screen data for certain portions of the requested web page. For example, as depicted in FIG. 3, host module 114 may instruct virtual machine 120A to retrieve screen data for the content web page 310 without any content for iFrame 312 or iFrame 314. Also in this example, host module 114 may instruct virtual machine 120B to retrieve screen data for the content associated with iFrame 312 and may instruct virtual machine 120N to retrieve screen data for the content associated with iFrame 314. The determination of which virtual machine should retrieve screen data for which portion of a requested web page may be made based on policy, as explained in more detail in a later section.

When host module 114 receives screen data from two or more guest modules, host module 114 assembles the graphical images represented by the sets of screen data and instructs host web browser 112 to display the assembled web page. In this way, the web page depicted in FIG. 3 may be shown to the user without the user being informed that content within iFrame 312 and content within iFrame 314 were retrieved in a different virtual machine than web page 310.

It may be advantageous to retrieve different portions of a web page from different virtual machines for security purposes. Content contained within an iFrame may contain malicious code. It is common for advertisements and the like to be included within an iFrame. Advertisements and the like may be served by a third party service. As a result, it is difficult for the operator of a web site to monitor content embedded within a web page of their web site for malicious code. By retrieving the content associated with an iFrame in a separate virtual machine, any malicious code that attempts to access unauthorized resources will be unable to access other portions of the web page, let alone access to sensitive resources outside of the virtual machine in which it executes.

Communication Between the Host Module and the Guest Module During a Browsing Session

The steps of FIG. 2 describe how the display of a single requested web page may be performed using a virtualized web browser. During the course of a normal web browsing session, a user will, naturally, interact with a displayed web page, either by clicking a link on the web page, entering and submitting text via a text box, and other more complex click and type interactions. Since different virtual machines may be responsible for retrieving different web pages, or even different portions of the same web page, any interaction of the user with a particular portion of a web page should be handled by the appropriate virtual machine. To do so, host module 114 and one or more guest modules will communicate with each other to support a user's interaction with a displayed web page.

When a user selects a link on web page, clicks a button, submits character data entered via the keyboard, and the like, host module 114 is notified that a user is submitting user input relative to a particular location on a web page. Host module 114 identifies the portion of a displayed web page to which the user input is directed. For example, host module 114 may identify a particular iFrame associated with the submitted character data or a particular link that was selected. In certain embodiments, the host module 114 also identifies where the position of a mouse cursor or any other input, such as input from a light pen, a finger on a display, and the like, relative to the web page. In this way, host module 114 may identify where the mouse pointer is relative to the web page to facilitate the performance of a mouse hover operation or any other such operation that requires the location of the mouse pointer or input mechanism relative to the web page.

Host module 114 identifies, based on policy and results of prior operation of the system, the specific virtual machine responsible for the portion displayed web page to which the user input was directed. Host module 114 then notifies the guest module within the identified virtual machine of the user input. For example, if host module 114 determines that virtual machine 120B is responsible for a web page, then host module forwards the user input to guest module 124B for processing.

Once guest module 124B receives the user input, guest module 124B will instruct VM web browser 122B to act on the user input by performing the action associated with the user input. For example, if the user input identifies a particular location on a web page over which the user clicked a mouse button, then VM web browser 122B will navigate the mouse pointer to the same location, perform a mouse click operation, and process the results. Note that VM web browser 122B will be displaying the same web page as host web browser 114, and so the user input may be processed against the web page displayed by host web browser 114 similarly as if host web browser 114 was actually processing the user input. Once VM web browser 122B has processed the user input (such as, for example, obtaining a requested web page from a remote location in response to the user's mouse click), guest module 124B either sends screen data for the resulting appearance of the content displayed by VM web browser 122B to host module 114, or host module 114 retrieves such screen data directly from virtual machine 120B, so that host module 114 may instruct host web browser 112 to display the screen data to the user.

Guest module 124B may send a request to host module 124B for any information about the user's web browsing session that is pertinent to the processing of the user input. If in this example guest module 124B requires one or more resources from host module 114 to properly process the user input, then guest module 124B may contact host module 114 to obtain such information. For example, if, in order to properly display a web page, guest module 124B determines that a particular cookie is needed, then guest module 124B may obtain the cookie by issuing a request for the cookie to host module 114.

If the user clicks a link on the displayed web page, guest module 124B may send a request to host module 124B to determine if guest module 124B can process a subsequent browsing action. If host module 114 allows this action, guest module 124B will instruct VM web browser 122B to retrieve the web page indicated by the selected link. On the other hand, if host module 114 denies guest module 124B permission to continue processing the web processing requests, host module 114 will instruct another virtual machine to retrieve the web content identified by the selected link. The decision of the host module 114 on whether to allow guest module 124B permission to continue processing browsing requests will be made based on policy data.

Persistently Storing Data and Injecting State Data

Generally, absent special considerations, virtual machines 120A, 120B, . . . 120N are not intended to be persisted ad infinitum. While one or more of virtual machines 120A, 120B, . . . 120N may be persistently stored in certain cases, more commonly such virtual machines will be destroyed or de-allocated when they are no longer required. Thus, the typical use case of virtual machines 120A, 120B, . . . 120N is to instantiate them as needed and de-allocate them when their use is concluded. Consequently, data stored within one of virtual machines 120A, 120B, . . . 120N may not be persisted.

As a result, in an embodiment, when a guest module determines that data within the virtual machine should be persistently stored, the guest module sends a request to host module 114 to persistently store the data within host 114. To persistently store data describing state changes made to the web browsing session (“state data”) at the virtual machine 120A, guest module 124A may send a request to persistently store the state data. Upon receipt of the request, host module 114 stores the data persistently on host 110. Host module 114 may persistently store data at host 110 at state data storage 130. State data storage 130 may be implemented by any mechanism capable of storing data, such as a database or a file system.

In some embodiments, certain state data may be persisted by updating host web browser 112. For example, if the state data which guest module 124A is requesting host module 114 to persistently store is a configuration setting change to the virtualized web browser, a change to the user's bookmarks, or a cookie, then such changes may be stored by updating host web browser 112. Host web browser 112 will thereafter persist such state changes.

Alternately, rather than persistently storing state data at host 110, data may be persistently stored in a virtual machine that is persisted. In such an embodiment, a guest module may communicate with an entity in a virtual machine to store state data within the virtual machine. This embodiment may be useful if it is desired to separate state data from host 110. For example, if there is a possibility of a malicious program residing in the host, by persistently storing the state data in a virtual machine, the malicious program will be unable to inspect the state data, thereby rendering the state data private and secure. In such an embodiment, rather than state data storage 130 residing in host 110 as depicted in FIG. 1, state data storage 130 will reside in a virtual machine, such as one of virtual machines 120A, 120B, . . . 120N, which is configured to be persisted.

The guest module running in each virtual machine has explicit and full visibility into the activity occurring within the virtual machine. The guest module can decide, based on and within the limits of policies contained within policy data, when the guest module should send resources or state data to host 110 to assist in servicing activity performed by the VM web browser. When a VM web browser within a virtual machine decides to update or save new resources, the guest module within that virtual machine may determine, based on the policies within the policy data, to send the information back to host module 114. Host module 114 may decide to either update or add to the data stored in state data store 130 using the information sent by the guest module. Host module 114 may also determine to send updates to any currently running virtual machines that are performing various other navigations or other browser actions based on policy settings and/or knowledge of what is the activity happening in each of the virtual machines. This resource coordination may also make use of the knowledge of what all the virtual machines are doing with applications and resources other than the virtualized web browser.

It will, on occasion, be necessary to inform a virtual machine about activities performed in a web browsing session that occurred outside of that virtual machine. To do so, state data for a web browsing session is “injected” into that virtual machine. FIG. 4 is an illustration that will be referenced in a discussion of injecting state data into a virtual machine according to an embodiment of the invention. Initially, with reference to FIG. 4, assume that VM web browser 122A is instructed to perform an action by guest module 124A that causes VM web browser 122A to change the state of the web browsing session of the user. Guest module 124A will be cognizant of any change in the web browsing state as guest module 124A monitors the activity performed by VM web browser 122A.

After guest module 124A determines that a state change in the web browsing session for the user has occurred in virtual machine 120A, guest module 124A consults policy data to determine whether such change should be persisted within system 100. The policy data that is consulted by guest module 124A in this regard may be implemented in a variety of ways. The policy data may reside within guest module 124A or may reside elsewhere, such as a persisted virtual machine dedicated to storing policy data. Policy data refers to data that defines one or more policies that are used to shape the behavior of one or more components of the virtualized web browser. Policy data will be described in greater detail below.

Alternately, guest module 124A may be implemented such that guest module 124A causes any state data describing a local change in the state of the web browsing session to be automatically sent to host module 114 rather than doing so based on a consultation with policy data. In such an embodiment, host module 114 may be designed to consult policy data to determine how to process any state data received from a guest module in such an embodiment.

In an embodiment, if guest module 124A determines that the change in state in the web browsing session should be persisted, then the guest module 124A causes state data that describes this change in state to be persistently stored. FIG. 4 depicts this as action 410 embodied as a request to persistently store the state data sent from guest module 124A to host module 114. While, as described above, embodiments may persistently store data using a variety of different mechanisms, the embodiment of FIG. 4 stores state data persistently at host 110 within state data storage 130. When host module 114 receives instruction 510 from guest module 124A, host module 114 stores the state data within state data storage 130 as shown in action 420. This act of host module 114 storing the state data within state data storage 130 need not be automatic, but instead, may be based upon consultation with policy data. For example, policies may be defined to determine whether state data should be persisted at all, whether the state data should be persisted using state data storage 130 or host web browser 112, etc.

The purpose of virtual machine 120A providing host 110 state data to persistently store is to ensure that the necessary information is available to notify components of the virtualized web browser of any relevant activity (or changes in state) that occur in other components of the virtualized web browser. Therefore, after persistently storing relevant state data concerning the activities of the web browsing session occurring in each virtual machine, embodiments send out (or “inject”) relevant information to virtual machines as necessary so the VM web browsers executing therein have all the necessary information to provide a seamless user experience.

Injecting state data into a virtual machine is illustrated in FIG. 4 in action 430. As shown by action 430, host module 114 is providing guest module 124B in virtual machine 120B state data. The state data provided to virtual machine 120B identifies information about how the user previously interacted with the virtualized web browser that will be used by VM web browser 122B in retrieving and/or rendering any content.

Note that not all state data for a user need be injected into each virtual machine. For security reasons, it is desirable to only expose the minimum amount of state data to a virtual machine necessary for the VM web browser executing therein to retrieve and render a requested web page properly. By “properly,” what is meant is that the requested web page looks and behaves as the user expects based on his or her past history interacting with web site. Said differently, a properly rendered web page takes into account all pertinent state data necessary to resolve the display all content therein. Policies defined by the policy data, therefore, will inject into a virtual machine only the state date which is deemed pertinent to the assigned responsibilities for that virtual machine.

To provide a concrete example, assume that virtual machine 120B is tasked with the responsibility of interacting with social media web sites. Further assume that policies defined within the policy data consider such social media web sites as posing a risk of infection of malicious code. Therefore, it would not be advisable to expose any malicious code that is inadvertently introduced into virtual machine 120B to any cookies associated with the user's sensitive information, such as bank account information, passwords, and the like. Consequently, in an embodiment, when host module 114 injects state data into a virtual machine, host module consults policy data, either stored within host 110 or within a virtual machine that is persistently stored, to identify state data that is pertinent to the assigned responsibilities of the virtual machine, so that only pertinent state data is injected therein.

Injecting state data into a virtual machine may also be performed to warm up a cache within the virtual machine. For example, if a user previously visited a particular web site, cache files for the web site may be persistently stored. If the user visits that web site again and a new virtual machine is instantiated to handle the navigation, the cache files associated with the particular web site may be injected into the newly instantiated virtual machine.

When the state information associated with a virtual machine is to be persisted beyond the lifetime of the virtual machine (as per host module 114), it is convenient to persist this information with an identifier related to the activity being executed in the virtual machine. For example, the top-level domain name (TLD) of the URL being rendered inside the virtual machine may be a convenient identifier. The identifier allows this information to be retrieved when it is needed, such as when this information is injected into a virtual machine created to render a URL with the same TLD as of the virtual machine being destroyed.

Policy Based Decision Making

In embodiments of the invention, the operation of host module 114 and guest modules 124A, 124B, . . . 124N is based, at least in part, upon policies defined in policy data. For example, host module 114 may consult one or more policies defined in policy data to (a) identify which virtual machine should be tasked with the responsibility of servicing a request to retrieve a web page, and/or (b) determine how to instruct a guest module, within the virtual machine designated responsible, to retrieve the web page. Policies may consider a host of factors in determining which virtual machine should service a request to retrieve a web page. For example, the web address, knowledge of any scripts executing on the parent web page, and whether the requested web page is in a new or existing web domain may all play a factor in determining which virtual machines retrieves the requested web page.

When host module 114 receives a subsequent request to display another web page, host module 114 determines, based on policy data accessible to host module 114, whether the same virtual machine that handled the retrieving and rendering of a previous requested web page should retrieve and render the newly requested web page. For example, the policy data may indicate that a newly requested web page has characteristics similar to a previous web page retrieved and rendered by virtual machine 120A. In such as case, host module 114 may task guest module 124A with retrieving and rendering the newly requested web page. In this way, the policy data may treat web pages within the same web page similarly so that all the web pages of a particular domain are serviced within the same virtual machine.

Alternately, the policy data may indicate that the newly requested web page can be processed within the same virtual machine but using a new web browser. In such a case, host module 114 may task guest module 124B with retrieving and rendering the newly requested web page using a newly instantiated web browser in virtual machine 120A other than VM web browser 122A.

Alternately, the policy data may indicate that the newly requested web page should be processed within a different virtual machine than any currently instantiated. In such a case, host module 114 may instantiate a new virtual machine and instruct a guest module, executing within the newly instantiated virtual machine, to retrieve and render the newly requested web page.

In an embodiment, the policy data discussed above is shown as policy data 140 in FIG. 1. In other embodiments not depicted in FIG. 1, policy data 140 may be persistently maintained in a persistently stored virtual machine.

Deallocating Virtual Machines in a Controlled Manner

In an embodiment, when a particular virtual machine is no longer required, that virtual machine may be de-allocated. As a result, when host module 114 receives notification that the user is closing the virtualized web browser, host module 114 may, without human intervention, de-instantiate any virtual machine associated with the web browsing session. Thus, any virtual machine that assisted in providing content to the virtualized web browser will be automatically de-instantiated in an embodiment as a result of the user closing the virtualized web browser.

Retrieving Content from Different Domains

A virtualized web browser of an embodiment will have the same visually appearance and support the same features as a traditional web browser. Therefore, like traditional web browsers, a virtualized web browser will support the use of tabs in an embodiment. However, a virtualized web browser may retrieve content to be displayed in a tab in a more secure manner than prior approaches.

In an embodiment, upon the virtualized web browser being instructed to display a new tab, the virtualized web browser displays the new tab without instantiating a new virtual machine. Thus, if a user were to repeated press “Control-T” or a similar mechanism to launch a new tab, the new tab may be created and displayed by the virtualized web browser without instantiating or assigning any virtual machines to retrieve content for the new tab. This advantageously minimizes memory usage of the virtualized web browser.

Once a user instructs the virtualized web browser to display a web page within a tab, host module 114 may consult policy data 140 to determine whether the requested web page may be retrieved and rendered in an existing virtual machine or if a new virtual machine should be instantiated.

In an embodiment, requested web pages from the same domain may be retrieved and rendered within the same virtual machine. In this way, the synchronization of certain resources, such as cache files, is simplified and/or expedited. Thus, if a user requests a web page from a domain in which another web page has already been fetched and rendered within an existing virtual machine, then the newly requested web page may be fetched and rendered within that same virtual machine. On the other hand, if the user requests a web page from a domain from which no web pages have previously been fetched, for example, then a new virtual machine may be instantiated in which to fetch and render that web page.

Synchronizing History Data

Embodiments of the invention seamlessly synchronize resources of a virtualized web browser, and in particular history data, across host 110 and virtual machines 120A, 120B, . . . 120N to present a completely native browser experience to the end user. History data is a type of state data. History data is data that describes a user's navigation history. History data may include the navigation history of the current session as well as web sites and resources previously visited during prior browsing sessions. By synchronizing history data across the virtualized web browser, the user is able to perform any type of operation involving history data in the same manner as in a traditional web browser even though web pages may be retrieved from a plurality of virtual machines.

In an embodiment, history data may include bookmarks for the user. History may also include one or more URLs visited by the user as well as titles of web pages and names of resources used. In order to perform certain operations on a web browser, such as back page and forward page, it is necessary to know the sequence and identity of visited web pages in each tab; therefore, in an embodiment, history data may also identify one or more actions that were performed with respect to a particular tab of the virtualized web browser.

Operations involving these types of resources will be performed seamlessly since any history data pertinent to the function of the various virtual machines will be merged correctly by host module 114. When new history data is created locally within a particular virtual machine, host module 114 is informed of the new state data so that it may be persistently stored and injected into other virtual machines as necessary. For example, if guest module 124A detects that new history data has been created within virtual machine 120A, then guest module 124A may notify host module 114 of the new history data. This may be accomplished in a variety of different ways by embodiments, e.g., guest module 124A may send host module 114 the new history data via a secure communication channel or guest module 124A may cause the new history data to be persistently stored and may notify host module 114 that new history data has been stored and may be retrieved as needed. In an embodiment, host module 114 causes any new history data sent from a virtual machine to be persistently stored so that host module 114 may inject the new history data, as needed, into appropriate virtual machines.

In an embodiment, we optionally do not update history data to identify all actions taken in a virtual machine. For example, if there is a redirect operation performed in a VM web browser, only the final or the first URL may be shared with the host and other VMs, rather than all URLs involved in the redirect.

In an embodiment, history data is used to update the visual appearance of host web browser. For example, back or forward buttons may be displayed as disabled (or “grayed out”) or active depending upon the available of appropriate history data to service such operations. When a user initiates the display of a menu in the host operating system that enables the user to navigate previously visited sites, history data will be used to perform the operation. For example, if the user performs a right click operation with his or her mouse to display a menu offering navigation options, or if the user clicks a back or forward button on the virtualized web browser, such navigation commands will be performed using history data obtained from the virtual machines on the system.

Synchronizing Cookies

Embodiments of the invention seamlessly synchronize resources of a virtualized web browser, and in particular cookie data, across host 110 and virtual machines 120A, 120B, . . . 120N to present a completely native browser experience to the end user. Cookie data is a type of state data. Cookie data is data that describes a user's cookies. Cookie data may include cookies dropped in the current session as well as cookies dropping in prior browsing sessions. By synchronizing cookie data across the virtualized web browser, the user is able to perform any type of operation involving cookie data in the same manner as in a traditional web browser even though web pages may be retrieved from a plurality of virtual machines.

In an embodiment, when host module 114 instructs a guest module to coordinate with a VM web browser to retrieve and render a requested web page, host module 114 provides the guest module cookie data. The cookie data identifies one or more cookies deemed to be pertinent to the retrieval of the web page. Rather than relying solely using a push model, certain embodiments may also employ a pull model where the guest module may send a request to host module 114 to ascertain whether there are any additional cookies for the user associated with an embedded web page comprised within the web page. In this way, host module 114 may provide to a guest module any cookie data which host module 114 deems pertinent to the retrieval of a requested web page. However, upon retrieving the requested web page, if the guest module determines that possession of one or more cookies would affect how the requested web page is rendered, then the guest module may communicate with host module 114 to determine if such cookies have been established for the user, and if so, then the guest module may obtain them from host module 114.

The type and amount of cookie data sent from host module 114 to a guest module may be configured using policies defined in the policy data. For example, in an embodiment, host module 114, based on consultation with policy data, may only sent to a guest module cookie data that identifies cookies associated with the top-level domain of the requested web page and does not identify any cookies associated with the domain of any embedded web pages comprised within the requested web page. On the other hand, in other embodiment, policy data may define a different set of policies, and host module 114 in that embodiment may provide, to a guest module, cookie data that identifies cookies associated with the top-level domain of the requested web page and any domain of any embedded web pages comprised within the requested web page. Embodiments may employ policy data that defines a variety of policies for specifying which cookies should be provided to a virtual machine.

Embodiments of the invention may store cookie data using a variety of different mechanisms. Cookie data may be stored in any location and in any manner that state data may be stored. Cookie data may be stored at state data storage 130 in an embodiment. In another embodiment, cookie data may be persistently stored by host web browser 112. In another embodiment, cookie data may be stored in a virtual machine that is persistently stored.

A guest module may employ a variety of mechanisms to determine when a VM web browser drops a cookie. For example, the guest module may detect the performance of set cookie operation via an API, a callback, or a plug-in to the VM web browser.

In an embodiment, a guest module may redirect processing of any set cookie instruction or get cookie instruction comprised within the web page to host module 114. In this way, host module 114 may become a central manager of all cookies throughout the virtualized web browser, regardless of which particular virtual machine is retrieving a web page.

Managing Display Issues

Embodiments of the invention enable a web page retrieved and rendered within a virtual machine by a VM web browser to be displayed upon a physical display device by host web browser 112 executing on host 110. Host module 114 assists in assembling the rendered content obtained from the host or from any virtual machine responsible in contributing rendered content for a web page displayed by host web browser 114.

Certain types of web content may be deemed secure while other types of web content may be deemed insecure. For example, web sites accessible over a secure connection (vis-à-vis a https connection) or web pages hosted internally on an Intranet may be deemed secure (i.e., low risk of comprising malicious software). Other public web sites available on the Internet may be deemed insecure due to the higher level risk that such sites may be infected with malicious code.

Embodiments may treat secure web sites different than insecure web sites. A virtualized web browser of an embodiment may interact with a secure web site using a VM web browser executing with a virtual machine having characteristics specifically tailored to interact with the secure web site. In the same vein, a virtualized web browser of an embodiment may interact with an insecure web site using a VM web browser executing with a virtual machine having characteristics specifically tailored to interact with the insecure web site.

A single web page may contain secure portions and insecure portions. For example, a child web page may be embedded within a parent web page using a HTML construct such as an “iFrame.” The parent web page may be deemed secure while the child web page may be deemed insure. In an embodiment, when a requested web page contains both secure and insecure content, a warning may be displayed to the user. The warning may inform the user that the requested web page contains content deemed insecure. The warning may allow the user to consent to assume the risk and continue with processing the web page. If the user wishes to proceed with retrieving the web page, then a new virtual machine may be instantiated for purposes of retrieving the insecure portions of the requested web page. The newly instantiated virtual machine will contains a guest module and a VM web browser. The newly instantiated guest module and VM web browser will cooperate to retrieve and render the insecure portions of the requested web page. Once host module 114 obtains screen data for the insecure and secure portions of the requested web page, host module 114 may assemble the rendered portions of the requested web page and instruct host web browser 112 to display the assembled web page.

Host module 114 may obtain screen data for a rendered portion of a web page in a variety of different ways. For example, in an embodiment, host module 114 may obtain screen data may accessing a frame buffer that stores data representing a rendered portion of a web page. Host module 114 may do so for each virtual machine responsible for rendering a portion of a requested web page. After obtaining all the pieces of the requested web page, host module 114 may assemble the pieces and instruct host web browser 112 to display the assembled web page.

In another embodiment, host module 114 may obtain screen data using an operating system protocol for displaying the contents of one frame in another frame. In this way, the rendered content displayed by a VM web browser may be identified and displayed by host web browser 112.

Note that it may be desirable in certain embodiments to configure a policy to disallow the display of certain types of content. For example, content originating from certain prohibited web sites or possessing certain undesirable characteristics, such as embedded graphics or text associated with one or more keywords may be prevented from being displayed. In such an embodiment, policy data may be stored which defines one or more polices that demarcate when certain content should or should not be displayed by host web browser 112. When host module 114 obtains screen data, host module 114 may consult the policy data to determine whether it is permissible to display the screen data. If it is not permissible to display a set of screen data, then host module 114 instructs host web browser 112 to display any portion of the web page which is allowed, but redacts any disallowed portions of the requested web page by causing such portions to be displayed blank or with a graphic that explains that the portion is not being displayed for violation of a policy.

In an embodiment, when the virtualized web browser comprises two or more tabs, each tab may be serviced by a separate VM web browser executing within a separate virtual machine.

On-Demand Unprotected Mode

In certain embodiments, a computer system may instantiate a virtual machine, upon demand, so as to execute a process or task within the virtual machine. When the process is closed or the task is completed, the virtual machine may be de-allocated. For example, a computer system may execute multiple virtual machines that each provides support for a browsing session associated with a tab of a web browser. For purposes of this specification, a “web session” or “web browsing session” may be generally considered to embody web browsing activity that begins on one web site and proceeds as a user clicks links to go to other pages in the initial domain or to other web sites, without entering a web address (e.g., in the browser address bar or an “Open” dialog box) or clicking a link that results in opening a new browser tab or window. A “web session” or “web browsing session” is therefore meant to cover browsing in a single tab. For example, if a user uses a single web browser to “surf the web” using two different tabs of the web browser, the activity associated with each tab of the web browser is a different web session or web browsing session as used herein.

As part of the virtualized web browsing environment, various policies may be configured to instruct the behavior of virtual machines in which web content is retrieved and rendered. For example, the use of JavaScript may be disallowed in a particular micro-VM instantiated using a particular template or external communication to particular IP addresses may be restricted in another virtual machine.

The operation of a particular web browsing session may be impeded or disrupted by certain virtual machine policies. For example, this may be because something in the code embedded within the web page conflicts with a security policy. In such a case, it is advantageous to allow certain users (such as a power user or IT administrator, for example) the ability to enter an “unprotected mode” in which rather than retrieving and rendering a web page within a virtual machine (which is subordinate to virtual machine security policies), the web page is retrieved and rendered within the host operating system (which is not subject to virtual machine security policies). Use of the unprotected mode allows IT administrators, developers, and the like to debug certain behavior problems of a web browsing session supported by a virtual machine because such behavior problems may be the result of security policies and/or other characteristics enforced by or associated with a virtual machine. By allowing certain web pages in a web browsing session to be rendered in the host operating system, the security measures may be bypassed and web pages that are not fully operational within a virtual machine may be allowed to function and operate as designed.

In various embodiments, the unprotected mode may be initiated in a number of different ways. A visual element, such as a button (perhaps residing on a browser toolbar) or a menu option, may be selected by a user to cause a web browsing session to enter unprotected mode.

In one embodiment, a user may visit a web site in a micro-VM as part of a web browsing session. As described earlier, the web site is rendered and displayed in a single micro-VM. Upon determining that particular desired functionality is not available (perhaps due to security restrictions imposed by the micro-VM or other restrictions introduced by the micro-VM paradigm), a user may request to enter an unprotected mode. A user interface element requesting confirmation may be displayed in response by an embodiment. Once the unprotected mode is initiated, the web page is re-rendered in the host operating system.

In some embodiments, a visual indicator is displayed to alert a user that unprotected mode is active and that subsequent content will be rendered by the host operating system. This could take any number of forms, such as the particular browser tab that is rendering web content in the unprotected mode being differentiated by color, an alert banner being displayed, or other type of visual or audio indicator.

In an embodiment, once a web browser is instructed to render a web page in an unprotected mode, the particular web page address (or the entire domain in some embodiments, depending on policy) is added to a “whitelist” so that subsequent visits to content on the whitelist will automatically be rendered in the unprotected mode without any confirmation actions needing to be taken.

Once a request to leave unprotected mode is received, a new micro-VM is instantiated and the current web page being rendered in the host is terminated and re-rendered in the new micro-VM. The visual indicator of being in unprotected mode is also removed.

In an embodiment, a “snapshot” of the host may be created upon entering and exiting unprotected mode, as well as at any time during the web browsing session being in unprotected mode. These snapshots may assist in diagnosing security issues resulting from the rendering of certain web page content in the host operating system. In an example embodiment, all activity related to the web session being rendered in the host during unprotected mode may be logged until the unprotected mode is terminated. This may assist technicians in diagnosing why a particular web site is not being properly rendered in a micro-VM.

FIG. 5 is a flowchart illustrating the functional steps of migrating a web browsing session between a virtual machine and a host operating system according to an embodiment of the invention. In step 510, a web session is supported by a micro-VM. For example, a user may type www.bank.com into a web browser address bar. In response, a micro-VM may be instantiated, and the web page associated with that URL may be retrieved and rendered within the micro-VM, and subsequently displayed by the user by the host operating system. The web browser may have multiple tabs open, in which case this web browsing session will be shown within one of the tabs of the web browser.

In step 520, a request to enter unprotected mode is received. In the above example, the user may find that she cannot log into www.bank.com because of a conflict with a policy or other constraint enforced by or upon the micro-VM. The user may be an administrator or belong to another group of users that are defined by policy as having the ability to enter unprotected mode. In an embodiment, users not belonging to this group or otherwise lacking such access privileges may not access unprotected mode.

In an embodiment, to enter unprotected mode, the user clicks a button on the web browser toolbar and a dialog box UI element is displayed asking for confirmation that the user wishes to enter unprotected mode. After the user confirms the action, the particular web site (in this example, www.bank.com) is migrating to the host operating system. In some examples, the current web address may be re-rendered, so the user is placed seamlessly back where she was, or only the root domain may be re-rendered and the user may have to navigate back to the particular point in the website where she was.

In some embodiments, not all currently-active browser tabs may execute in unprotected mode. In the current example, only the www.bank.com tab is being rendered in the host, while all other tabs, even newly-created ones, are supported by virtual machines (i.e., the content displayed by those tabs are still retrieved and rendered within a virtual machine). In other examples, all browsing activity, once unprotected mode is activated, may be migrating to the host. The particular behavior may be defined by policy.

In step 530, once unprotected mode has been successfully entered, a visual cue is displayed that indicates unprotected mode has been activated. The visual cue may take many forms. For example, a particular browser tab in unprotected mode may be colored red or some other color indicating that the web content is being retrieved and rendered in the host operating system. Alternately and/or additionally, graphic banners, images, or other sensory cues may be used to inform the user that that the web browsing session is in unprotected mode.

In step 540, a request for a web browsing session to exit the unprotected mode is received. A request to exit the unprotected mode may be initiated by a variety of different actions. In an embodiment, actions such as typing a web address in the address bar of a web browser, dragging a file comprising a web address into the browser window, or closing the browser tab may constitute a request to terminate unprotected mode (or may terminate it immediately in some embodiments) in that web browsing session. As another example, the user may click the visual cue or other graphic designed to inform the user that the web browsing session is in unprotected mode to turn unprotected mode off.

Upon receiving the request to exit unprotected mode in a web browsing session, support for the web session is transferred from the host operating system to a virtual machine, which may be newly instantiated just for that purpose.

In an embodiment, the user may be presented with a choice of micro-VM templates in which to instantiate a virtual machine in which support for the web browsing session is to be migrated. A web browsing session may have failed initially because the micro-VM in which the browsing activity was supported did not have enough memory, lacked certain system files, or otherwise was associated with a certain characteristic. The user may select migrate support for the web browsing session in step 540 to a different type of virtual machine by selecting a different type of template in this manner, thereby providing further assistance with debugging the proper operation and behavior of rendered web pages of an embodiment. In certain embodiments, the user may not be able to select such a template or this decision may be performed transparently to the user through a consultation with a policy.

According to an embodiment, the approaches described herein are envisioned as being performed in the context of a host operating system executing at least one micro-virtual machine (or micro-VM), where instead of virtualizing multiple operating systems, the micro-VM (via a micro hypervisor or microvisor) isolates (via hardware and/or software) each application task within a single running OS in a lightweight micro-VM. In an embodiment, a microvisor uses hardware virtualization to guarantee that micro-VMs are isolated from the OS and each other. In this way, each untrustworthy task is automatically isolated within a micro-VM that has no access to enterprise data or networks, and which cannot modify the desktop. In one embodiment, a group of micro-VMs may be a plurality of virtual machines executing in a computing environment, where each task executes in a separate virtual machine instantiated for the particular task. Thus, embodiments of the invention may be employed with a computer system having many instantiated virtual machines at any given time.

Extensions

Note that embodiments of the invention have been chiefly described with reference to a virtualized web browser. However, the principles presented herein are equally application to other types of applications. Indeed, the teachings described above are equally applicable to any type of virtualized application, such as a virtualized email client or virtualized email server. In such an embodiment, rather than retrieving and rendering web pages within virtual machines, each virtual machine may retrieve and render email or email attachments. Host 110 may be implemented on a cell phone, tablet PC, and the like, and virtual machines 120A, 120B, . . . 120N may reside in a data center or other remote location. When a user instructs the cell phone or tablet PC to display an email or an email attachment, the request could be routed to a particular virtual machine, which retrieves the email, renders the email or email attachment to produce screen data, and sends the screen data to the cell phone or tablet PC for display.

Similarly, applications other than a web browser may enter and exit unprotected mode. For example, the discussion of FIG. 5 may be equally applicable to other types of applications other than a web browser. In this way, applications such as an email client, a word processing application, and the like may enter and exit unprotected mode.

Hardware Mechanisms

FIG. 6 is a block diagram that illustrates a computer system 600 upon which an embodiment of the invention may be implemented. In an embodiment, computer system 600 includes processor 604, main memory 606, ROM 608, storage device 610, and communication interface 618. Computer system 600 includes at least one processor 604 for processing information. Computer system 600 also includes a main memory 606, such as a random access memory (RAM) or other dynamic storage device, for storing information and instructions to be executed by processor 604. Main memory 606 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 604. Computer system 600 further includes a read only memory (ROM) 608 or other static storage device for storing static information and instructions for processor 604. A storage device 610, such as a magnetic disk or optical disk, is provided for storing information and instructions.

Computer system 600 may be coupled to a display 612, such as a cathode ray tube (CRT), a LCD monitor, and a television set, for displaying information to a user. An input device 614, including alphanumeric and other keys, is coupled to computer system 600 for communicating information and command selections to processor 604. Other non-limiting, illustrative examples of input device 614 include a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor 604 and for controlling cursor movement on display 612. While only one input device 614 is depicted in FIG. 6, embodiments of the invention may include any number of input devices 614 coupled to computer system 600.

Embodiments of the invention are related to the use of computer system 600 for implementing the techniques described herein. According to one embodiment of the invention, those techniques are performed by computer system 600 in response to processor 604 executing one or more sequences of one or more instructions contained in main memory 606. Such instructions may be read into main memory 606 from another machine-readable medium, such as storage device 610. Execution of the sequences of instructions contained in main memory 606 causes processor 604 to perform the process steps described herein. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement embodiments of the invention. Thus, embodiments of the invention are not limited to any specific combination of hardware circuitry and software.

The term “machine-readable storage medium” as used herein refers to any tangible medium that participates in storing instructions which may be provided to processor 604 for execution. Such a medium may take many forms, including but not limited to, non-volatile media and volatile media. Non-volatile media includes, for example, optical or magnetic disks, such as storage device 610. Volatile media includes dynamic memory, such as main memory 606.

Non-limiting, illustrative examples of machine-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any other medium from which a computer can read.

Various forms of machine readable media may be involved in carrying one or more sequences of one or more instructions to processor 604 for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a network link 620 to computer system 600.

Communication interface 618 provides a two-way data communication coupling to a network link 620 that is connected to a local network. For example, communication interface 618 may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface 618 may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, communication interface 618 sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

Network link 620 typically provides data communication through one or more networks to other data devices. For example, network link 620 may provide a connection through a local network to a host computer or to data equipment operated by an Internet Service Provider (ISP).

Computer system 600 can send messages and receive data, including program code, through the network(s), network link 620 and communication interface 618. For example, a server might transmit a requested code for an application program through the Internet, a local ISP, a local network, subsequently to communication interface 618. The received code may be executed by processor 604 as it is received, and/or stored in storage device 610, or other non-volatile storage for later execution.

In the foregoing specification, embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Thus, the sole and exclusive indicator of what is the invention, and is intended by the applicants to be the invention, is the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of such terms as used in the claims. Hence, no limitation, element, property, feature, advantage or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. 

What is claimed is:
 1. A non-transitory computer-readable storage medium that stores one or more sequences of instructions, which when executed by one or more processors, causes: a first virtual machine, executing on a computer system, retrieving and rendering content for a web session; upon receiving a request for the web session to enter an unprotected mode, migrating support for the web session from the first virtual machine to a host operating system of the computer system, wherein, in the unprotected mode, web sessions are supported by the host operating system rather than by a virtual machine; after migrating support for the web session to the host operating system, displaying a visual cue indicating that the unprotected mode is active for the web session; and upon receiving a request for the web session to exit the unprotected mode, migrating support for the web session to a second virtual machine executing on the computer system and removing the visual cue.
 2. The non-transitory computer-readable storage medium of claim 1, wherein the web session is displayed within a first tab of a web browser, and wherein the web browser comprises at least one other tab which is configured to display content that is retrieved and rendered by a different virtual machine than either the first virtual machine or the second virtual machine while the web session displayed by the first tab is in unprotected mode.
 3. The non-transitory computer-readable storage medium of claim 1, wherein the first and second virtual machines are instantiated to execute the web session therein.
 4. The non-transitory computer-readable storage medium of claim 1, wherein execution of the one or more sequences of instructions further causes: creating a snapshot of the host operating system upon entering and exiting the unprotected mode.
 5. The non-transitory computer-readable storage medium of claim 1, wherein execution of the one or more sequences of instructions further causes: upon the web session entering the unprotected mode, logging activity performed in support of the web session within the host operating system until the unprotected mode is exited.
 6. The non-transitory computer-readable storage medium of claim 1, wherein execution of the one or more sequences of instructions further causes: upon receiving the request for the web session to exit the unprotected mode, adding at least one web site address, visited while unprotected mode was active, to a whitelist so that subsequent visits to the at least one web site will automatically be rendered in the unprotected mode.
 7. The non-transitory computer-readable storage medium of claim 1, wherein the second virtual machine is created from a different template than the first virtual machine.
 8. The non-transitory computer-readable storage medium of claim 1, wherein receiving the request for the web session to exit the unprotected mode further comprises: upon receiving user input that identifies a selected template, instantiating the second virtual machine using the selected template.
 9. The non-transitory computer-readable storage medium of claim 1, wherein receiving the request for the web session to exit the unprotected mode further comprises: determining that the request for the web session to exit the unprotected mode has been received by detecting that the visual cue has been clicked, a menu option has been selected, a new web address has been requested using the web browser, or a web browser tab has been closed.
 10. An apparatus, comprising: one or more processors; and one or more non-transitory computer-readable storage mediums storing one or more sequences of instructions, which when executed, causes: a first virtual machine, executing on a computer system, retrieving and rendering content for a web session; upon receiving a request for the web session to enter an unprotected mode, migrating support for the web session from the first virtual machine to a host operating system of the computer system, wherein, in the unprotected mode, web sessions are supported by the host operating system rather than by a virtual machine; after migrating support for the web session to the host operating system, displaying a visual cue indicating that the unprotected mode is active for the web session; and upon receiving a request for the web session to exit the unprotected mode, migrating support for the web session to a second virtual machine executing on the computer system and removing the visual cue.
 11. The apparatus of claim 10, wherein the web session is displayed within a first tab of a web browser, and wherein the web browser comprises at least one other tab which is configured to display content that is retrieved and rendered by a different virtual machine than either the first virtual machine or the second virtual machine while the web session displayed by the first tab is in unprotected mode.
 12. The apparatus of claim 10, wherein the first and second virtual machines are instantiated to execute the web session therein.
 13. The apparatus of claim 10, wherein execution of the one or more sequences of instructions further causes: creating a snapshot of the host operating system upon entering and exiting the unprotected mode.
 14. The apparatus of claim 10, wherein execution of the one or more sequences of instructions further causes: upon the web session entering the unprotected mode, logging activity performed in support of the web session within the host operating system until the unprotected mode is exited.
 15. The apparatus of claim 10, wherein execution of the one or more sequences of instructions further causes: upon receiving the request for the web session to exit the unprotected mode, adding at least one web site address, visited while unprotected mode was active, to a whitelist so that subsequent visits to the at least one web site will automatically be rendered in the unprotected mode.
 16. The apparatus of claim 10, wherein the second virtual machine is created from a different template than the first virtual machine.
 17. The apparatus of claim 10, wherein receiving the request for the web session to exit the unprotected mode further comprises: upon receiving user input that identifies a selected template, instantiating the second virtual machine using the selected template.
 18. The apparatus of claim 10, wherein receiving the request for the web session to exit the unprotected mode further comprises: determining that the request for the web session to exit the unprotected mode has been received by detecting that the visual cue has been clicked, a menu option has been selected, a new web address has been requested using the web browser, or a web browser tab has been closed.
 19. A method, comprising: a first virtual machine, executing on a computer system, retrieving and rendering content for a web session; upon receiving a request for the web session to enter an unprotected mode, migrating support for the web session from the first virtual machine to a host operating system of the computer system, wherein, in the unprotected mode, web sessions are supported by the host operating system rather than by a virtual machine; and upon receiving a request for the web session to exit the unprotected mode, migrating support for the web session to a second virtual machine executing on the computer system.
 20. The method of claim 19, further comprising: after migrating support for the web session to the host operating system, displaying a visual cue indicating that the unprotected mode is active for the web session; and upon migrating support for the web session to the second virtual machine executing on the computer system, removing the visual cue. 